Fuses, or more specifically micro fuses, can be used to encode (store) information in devices such as removable printer components (e.g., ink cartridges) used in printer systems. For example, a device can include a number of fuses. A blown fuse has a higher, or substantially open-circuit, resistance, while a non-blown fuse has a lower, or substantially closed-circuit, resistance. Information can be encoded depending on which fuses are blown or the particular combination of blown fuses. In a printer system, the type of information encoded may include, for example, identification of the type of product, the amount of ink provided by an ink cartridge, and the value of a thermal sense resistor associated with the ink cartridge.
The fuses may be blown during the manufacturing process or afterwards. Oftentimes there is difficulty in reliably blowing the fuses on a consistent basis. Variability in manufacture can result in some fuses blowing at a given voltage while others will not. This can result in some fuses that are intended to exhibit a substantially open-circuit resistance exhibiting a substantially closed-circuit resistance instead. Fuses can also “under blow,” meaning that they are partially but not completely blown. A higher voltage can be used to help ensure that the appropriate fuses will reliably blow. However, too much voltage can cause fuses to “over blow,” meaning that they blow too vigorously, perhaps causing damage to other layers of the fuse structure.
Variability in temperature from one fuse to another is another factor that contributes to the difficulty in blowing fuses reliably and consistently.
Not only do the factors described above combine to increase the uncertainty that a fuse can be blown, but they also introduce uncertainty into the fuse-blowing process. For example, it can be more difficult to identify beforehand what voltage should be used to blow the appropriate fuses.
For these and other reasons, there is a need for the present invention.